Coded signaling apparatus



July 3, 1951 H. G. BLOSSER ETAL CODED SIGNALING APPARATUS 2 Sheets-Shed 2 Filed NOV. 23, 1946 INVENTORS.

. QQ ESQ Herman 6i. Blwwrmd BY Fpa .ZVz'cIzoLrazz Patented July 3, 1951 UNITED STATES RATENT OFFICE GUIDED SIGNALING APPARATUS Pennsylvania Application November 23, 1946, Serial No. 711,964

9 Claims.

Our invention relates to coded railway signaling apparatus and particularly to improved code detecting means.

In some instances where a polarized code is utilized, coded energy of one polarity is used for the control of a vital or a safety function, such as release of approach looking or the control of highway crossing signals, while coded energy of the opposite polarity is used for the control of a non-safety function, such as approach lighting of sginals or the supply of cab signal control energy to the track rails.

In coded signaling systems, code following operation of a track or other relay is frequently detected by means of two slow release relays, the first of which is energized when the code following relay contacts occupy one position, and

the other or second of which is energized when the contacts of the code following relay occupy their other position provided the first slow release relay is picked up. Energization of the second slow release relay is dependent on alternate operation of the code following relay contacts to each of their two positions, so vital circuits may be governed by contacts of the second slow release relay.

For the detection of operation of a code following relay where non-safety circuits are to be controlled, a slow release relay energized when contacts of the code following relay are in the position to which they are operated by an impulse of energy may be used, and the non-safety circuits may then be controlled by this slow release relay.

From the foregoing it will be seen that in the usual arrangement for detecting a code which controls a vital function two relays are necessary, while a single relay may be used for detecting a code which controls a non-vital function. Accordingly, in a system where code of one polarity is used for controlling a vital function and code of the opposite polarity is used for controlling a non-vital function, code detecting equipment arranged in the usual manner requires the use of three slow release relays.

An object of our invention is to provide improved means for detecting polarized coded energy, using only two slow release relays.

Another object of our invention is to provide improved means for detecting polarized code, one polarity of which is used for the control of safety functions and the other polarity of which is used for the control of non-safety functions.

A further object of our invention is to provide improved code detecting means comprising two slow release relays which at times are employed jointly to detect operation of a code following relay governing a vital or safety function, and one of which is at other times employed to detect operation of a different code following relay which governs a non-vital function.

Other objects of our invention and features of novelty will be apparent from the following description taken inconnection with the accompanying drawings.

We shall describe three forms of code detecting apparatus embodying our invention, and shall then point out the novel features thereof in claims.

In practicing our invention, we provide a first and a second code following relay one of which is operated at times and the other of which is operated at other times. In addition, we provide a first and a second slow release relay. When the first slow release relay is released the circuit of the second slow release relay is established when the second code following relay responds to coded energy. When the first code following relay responds to coded energy its contacts, when in one position, establish a circuit for the first slow release relay, and the contacts of the first code following relay, when in their other position, establish a circuit for the second slow release relay provided the contacts ofthe first slow release relay are picked up. Accordingly, the second slow release relay at times detects operation of the second code following relay and at other times cooperates with the first slow release relay to detect operation of the first code following relay.

Circuits governing vital or safety functions are connected over front contacts of the first and second slow release relays in series, while circuits governing non-vital or non-safety functions are controlled by contacts of the second slow release relay.

In the drawings, Fig. 1 is a diagrammatic view of a section of railway track equipped with a coded signaling system embodying our invention.

2 is a diagrammatic view of a modification of the equipment shown in Fig. l, and

3 is a diagrammatic view of cut section apparatus which embodies our invention and may be used in connection with the arrangements shown in Fig. l or 2.

In the drawings similar reference characters refer to similar parts in each of the three views.

Refer lg to Fig. 1, there is shown therein a section of railway track 2T having track rails l .nd 2 which are isolated from the rails of the adjacent sections IT and 3T by the usual insulatecl joints 3. Traffic normally moves through this section in the direction indicated by the arrow, that is, from left to right. A signal S2, which as shown, is of the colorlight type having a green lamp G and a red lamp R, is located at the left-hand or entering end of section 2T and governs the movements of traffic into section 2T. A similar signal S3 located at the right-hand or leaving end of section 2T governs the movement of traffic into section 3T. Signals S2 and S3 are arranged so that they are lighted only during occupancy of the section in the rear of the section which they govern, that is, signal S2 is lighted when section IT is occupied, and signal S3 is lighted when section 2T is occupied. Approach lighting of signals is not considered as a safety function and failure of the lamps of a signal to be lighted on the approach of a train will not create a hazardous situation since the operating rules normally provide that an unlighted signal is to be considered as a stop signal. It is assumed that at the location of signal S3, it is desired to provide a circuit for the release of approach locking, control of highway crossing warning signals, or some other safety function, which is governed by occupancy of sections IT and 2T. The control of these circuits is a vital or safety function since failure of these circuits to be interrupted on the approach of a train might create a hazardous condition.

Signal S2 is controlled by master code energy supplied from the leaving end of section 2T, and the approach lighting of signal S3 and the control of the approach circuit are governed by impulses of feed back energy which may be of either normal or reverse polarity and is supplied from the entering end of section 2T.

The apparatus located at the entering end of track section 2T includes a code following track relay 2TR, which is of a type the contacts of which pick up when and only whenenergy iiows through the relay winding in the direction shown by the arrow, that is, from right to left; a track relay ITR, the contacts of which are released when the track section IT is occupied, and are picked up when section IT is unoccupied; an impulse relay IR which is supplied with energy from an impulse transformer IT; slow release relays ZFISA and ZBSA; and a battery ZFB for supplying feed back energy to the section rails I and 2.

The apparatus located at the exit end of track section 2T includes a coding device CT; a code transmitting relay CTM governed by the coding device CT; a normal feed back track relay PVR of a type the contacts of which pick up when and only when energy flows through the relay winding from right to left; a reverse feed back track relay NVR which is of a polar stick type having stay-where-put contacts, and having two windings; a first slow release relay PFSA; a second slow release relay PBSA; and a relay BBSA for controlling signal 3, which relay may be governed in a similar manner to that hereinafter described for relay ZBSA.

At each signal location a source of direct current energy, not shown, is provided, whose positive and negative terminals are denoted as B and C, respectively.

The equipment as shown in the drawings is in its normal condition, with sections IT, 2T and ET unoccupied. At this time coding device CT operates its contact It between its two positions continuously at one or more given frequencies,

7 back battery ZFB to the section rails.

for example, '75 or 180 complete cycles per minute. The code transmitting relay CTM is energized over a circuit governed by contact IQ of coding device CT. Accordingly, the relay CTM picks up and releases its contacts at a given frequency dependent upon the frequency of the coding device CT. When the contact I2 of relay CTM moves to its pickcd-up position, a circuit is established for supplying energy from battery 2TB over the section rails I and 2 to relay ZTR. This circuit is traced from the positive terminal of track battery 2TB over front contact i2 of relay CTM to track rail I, over rail I, back contact I4 of relay IR, which at this time is released, through the winding of relay 2TR from right to left, and over rail 2 to the negative terminal of track battery 2TB. The direction of flow of energy in the winding of track relay ZTR is such that its contacts pick up. When the contacts of track relay 2TB move to their picked-up position, a circuit is established to supply energy to the upper half of the primary winding I8 of the impulse translormer IT, while the circuit of the lower half of this winding is interrupted. An impulse of energy is thereby induced in secondary winding 29 of transformer IT and is supplied to the winding of the impulse relay IR. This relay is of a type the contacts of which pick up when and only when energy flows through the winding of the relay in a selected direction. The equipment is arranged so that the direction of flow of energy of the impulse induced in secondary winding 29 of transformer IT when the contacts of relay ZTR move to their picked-up position is such as to cause the contacts of relay IR to remain in their released position.

After a short time interval the contacts of coding device CT move to their released position and contact I0 interrupts the circuit for energizing the code transmitter CTM. When relay CTM releases, its contact l2 interrupts the supply of energy to section rails I and 2 from the track battery 2TB, and connects the feed back track relays PVR and NVR in series across the section rails I and 2.

Relay ZTR will now release due to the interruption of the supply of energy from track battery 2TB. On release of relay 2TR its contact l6 interrupts the supply of energy to the upper half of the primary winding of transformer IT and establishes a circuit for energizing the lower half of the primary winding I8 of transformer IT. As a result an impulse of energy is induced in the secondary winding 20 of transformer IT and this impulse of energy flows in such a direction as to cause the relay IR to pick up its contacts.

When the impulse relay IR picks up, its contact I4 interrupts the circuit previously traced for connecting the track relay ZTR across the track rails I and 2 and establishes a connection for supplying feed back energy from the feed At this time track relay ITR is picked up as track section IT is assumed to be unoccupied, and when relay IR picks up a circuit is established for supplying energy from feed back battery ZFB to the track rails in such a manner that rail I has positive polarity with respect to rail 2. This circuit is traced from the positive terminal of battery ZFB over front contact 22 of relay ITR and over front contact I4 of relay IR to rail I, while the negative terminal of battery 2FB is connected over front contact 24 of relay ITR to rail 2. At the leaving end of section 2T the feed back ens ergy flows from rail I over contact I2 of relay CTM in its released position, through the winding 26 of relay NVR from right to left, and through the winding of relay PVR from right to left to rail 2. The flow of energy through the winding 26 of relay NVR is in such a direction as to cause the contact of this relay to move from its left-hand or normal position to its right-hand or reverse position, and the flow of energy through the winding of relay PVR is in such a direction as to cause the contact of this relay to move from its released to its picked-up position.

After a short time interval the relay IR releases and contact I4 interrupts the circuit previously traced for supplying feed back energy to the track rails I and 2 and establishes the connection between the track relay 2TB and the rails I and 2. When the supply of energy to the relays NVR and PVR. is interrupted by the release of contact I4 of relay 1R, the contact of relay PVR releases. However, the contact of relay NVR, which is a polar stick type of relay, remains in the position to which it was last operated, in this case the reverse position.

After a short time interval the contacts oi coding device CT again move to their picked-up position and contact I of coding device CT again establishes the circuit for energizing relay CTM. When contact I2 of relay CTM picks up, track battery 2TB is again connected to the section rails I and 2, and the cycle of operation above described is repeated.

Accordingly, it will be seen that with the equipment operating in its normal condition the contacts of relay 2TB. are alternately picked up and released by energy supplied from the track battery 2TB at the leaving end of the section, and during the periods in which track relay 2TR is released, feed back energy is supplied from the entering end of the section from feed back battery 2FB over the section rails I and 2 to the feed back relays PVR and NVR at the leaving end of the section.

Each time track relay 2TB picks up, its contact 28 establishes a circuit to suply energy to the slow release relay ZFSA, and each time contact 28 of relay 2TB moves to its released position a circuit is established for supplying energy over front contact 30 of relay ZFSA to slow release relay 2BSA. Accordingly, relay ZBSA is energized at this time, and establishes a circuit over which energy may be supplied to the green lamp G of signal S2. However, since track relay ITR is assumed to be picked up this circuit is interrupted by contact 34 of relay ITR.

At this time the relay PVR is alternately picked up and released by the feed back energy supplied over the section rails I and 2 from feed back battery ZFB. During the picked-up periods of contact 36 of relay PVR energy is supplied to slow release relay PFSA with the result that its contacts are picked up.

Relay NVR operates its contact to its reverse position upon the supply of each impulse of feed back energy having a normal polarity, and during the time interval in which the contacts of relay CTM are picked up, energy is supplied to the .local winding 40 of relay NVR. When relay PFSA is picked up this energy is of the polarity such that the contact of relay NVR is operated to its normal position. This energy is supplied over the circuit which is traced from terminal B, over front contact 42 of relay PFSA, which, as explained above, is picked up at this time,

throughthe winding 40 of relay NVR from left 6 to right, over front contact 44 of relay CTM, and over front contact 46 of relay PFSA to terminal C.

When relay CTM releases, the supply of energy to the winding 40 of relay NVR is interrupted, but the contact of relay NVR will remain in its normal position until feed back energy supplied to winding 26 of the relay moves the relay contact to its reverse position.

It will be seen, therefore, that at this time the contact 36 of relay PVR is alternately moved between its picked-up and its released position, while contact 38 of relay NVR is alternately operated between its reverse and its normal posi-' tion.

As stated above, when contact 36 of relay PVR moves to its picked up position, it establishes the circuit for supplyin energy to the winding of relay PFSA. When the contact 36 of relay PVR is released and relay NVR operates its contact 38 to its normal position, a 'circult is established for supplying energy to relay PBSA. Accordingly, at this time relays PFSA and PBSA are alternately energized and their contacts are picked up.

Since both relays PFSA and PBSA are picked up, a circuit is established to supply energy to the approach-controlled circuit from terminal B over front contact 58 of relay PBSA, and front contact at of relay PFSA.

The circuit for selecting the green or the red lamp of signal S3 is controlled by contact 53 of relay 3BSA, which may be controlled in a manner similar to that previously explained for relay ZBSA so as to reflect traillc conditions in the section 3T. However, at this time no energy is supplied to the lamps of signal S3 due to the interruption of the circuit by contact 48 of relay PBSA. With the equipment operating in its normal condition as previously described, it is now assumed that a train moving from left to right enters section IT. As a result relay ITR releases and its back contact 34 establishes the circuit including front contact 32 of relay ZBSA for supplying energy to the green lamp G of signal S2.

In addition, contacts 22 and 24 of relay ITR move to their released position, causing the polarity of feed back energy supplied from the feed back battery ZFB to the track rails I and 2 to be reversed. The supply of master code energy from the track battery 2TB over section rails I and 2 to track relay 2TB remains as previously described. However, the circuit for supplying feed back energy from the battery 2F'B is now traced from the positive terminal of battery 2FB over back contact 24 of relay ITR, rail 2,

through the winding of relay PVR from left to right, through the winding 26 of relay NVR from left to right, over back contact I2 of relay CTM, rail I, over front contact I4 of relay IR, and over back contact 22 of relay ITR to the negative terminal of battery ZFB. The direction of the flow of the reverse polarity feed back energy through the winding of relay PVR. is such as to be ineffective to pick up the contact of relay PVR and to hold it in its released position in which it interrupts the circuit of relay PFSA so the contacts of relay PFSA release and remain released. The flow of energy through the winding 26 of relay NVR is in such a direction as to cause the relay NVR to move its contact 38 to its normal position.

The relay PFSA is slow in releasing, and in the period prior to its release the energy supplied to the winding 40 of relay NVR over the circuit governed by contact 44 of relay CTM is of the same polarity as that supplied to the winding 25. Accordingly, the contact 38 of relay NVR remains in its normal positionruntil relay PFSA releases and as. long as contact 38 of relay NVR remains in its normal position, energy is supplied to the winding of relay PBSA and its contacts remain in their picked-up position.

When relay PFSA releases, the polarity of energy supplied to the winding of relay NVR upon the closing of front contact 34 of relay CTM is reversed and energy is now supplied to winding Mlby a circuit which is traced from terminal B over back contact of relay PFSA, over front contact 44 of relay CTM, through the winding #0 of relay NVR from right to left, and through back contact 42 of relay PFSA to terminal C. This energy moves the contact of relay NVR to its reverse position in which it interrupts'the circuit of relay PBSA.

When impulses of feed back energy of reverse polarity are subsequently received over the rails l and 2, the contact 36 of relay PVR remains released and contact 38 of relay NVR. is moved to its normal position if it is not already in that position. When contact it of coding device CT moves to its picked-up position it causes energy to be supplied to relay CTM and contact M of relay CTM establishes the circuit for supplying energy to winding 48 of relay NVR. The energy which now flows through winding All of relay NVR is of such polarity as to cause contact 38 of relay NVR to move to its reverse position. As a result, the contact 38 of relay NVR interrupts the circuit for supplying energy to relay PBSA.

When relay CTM releases, its back contact 12 again establishes the circuit for connecting the relays PVR and NVR across the section rails l and 2, and relay NBR again receives an impulse of energy flowing in the direction to operate its 1 contact to its normal position to again establish the circuit for energizing relay PBSA.

Accordingly, after release of relay PFSA the contact of relay NVR is moved to its reverse position by energ supplied to the winding cc during the picked-up periods of relay CTM, while during the released periods of relay CTM the contact of relay NVR is moved to its left-hand or normal position by the impulses of feed back energy supplied over the track rails. As a result of the recurrent movement of contact 33 of relay NVR to its normal position the relay PBSA is maintained energized so that its contact 48 interrupts the circuit of the lamps of signal S3. At this time, as relay PFSA is released, its contact interrupts the approach-controlled circuit.

When the train under consideration passes signal S2 and enters track section 2T, the track relay 2TB. is shunted and its contacts remain released. As a result the impulse relay IR is no longer supplied with energy from impulse transformer IT and the supply of feed back energy from battery ZFB to the section rails l and 2 is thereby interrupted. Additionally, when relay 2TB, releases, the supply of energy to relay 2FSA over front contact 28 of relay 2TR is interrupted and after a short time interval relay ?FSA releases and interrupts the circuit for supplying energy to relay 2338A, and its contacts will subsequently release, thereby interrupting the supply of energy to the green lamp G of signal S2, and establishing the supply of energy to the red lamp R of signal S2.

When the supply of feed back energy from the 8 feed back battery 2FB is interrupted by the entrance of a train into the track section 2T, the supply of energy to the winding 26 of relay NVR is interrupted. The supply of energy to the winding it: of relay NVR. over the circuit controlled by front contact 54 of relay CTM is continued, however, and these impulses cause the contact of relay NVR to move to its reverse position and remain there. As a result the periodic supply of impulses of energy to the winding of relay PBSA over back contact 35 of relay PVR and contact 38 of relay NVR is cut off and relay PBSA releases. When relay PBSA releases a circuit is established for supplying energy to the'lamps of signal S3, and may be traced from terminal B over back contact 48 of relay PBSA, over a contact of relay SBSA, to the green lamp G of signal S3 to terminal C.

When the rear of the train passes out of section IT, relay ITR picks up and its pole changing contacts 22 and 24 again establish the connections which cause the energy supplied from battery ZFB to be of the polarity in which track rail I is positive with respect to rail 2. However, at this time as the train occupies section 2T, relay ZTR is released and the supply of energy to relay IR is interrupted. Accordingly, energy from battery 2FB is not supplied to section rails l and 2 at this time.

Additionally, when relay ITR picks up, its contact 3-3 interrupts the circuit previously traced for supplying energy to the lamps of signal S2.

When the train passes signal S3 and enters track section 3T, relay SBSA, which may be controlled in a similar manner to that previously described for relay ZBSA, releases and its contact 53 interrupts the circuit for supplying energy to the green lamp G of signal S3 and establishes the circuit over its back contact for lighting the red lamp R of signal S3.

When the train vacates section 2T, master code energy supplied from battery 2TB to the sectionrails I and 2 again feeds to the relay 2TB. Accordingly, track relay 2TB again follows code and its contact 28 will again establish the circuits for supplying energy to the slow release relays ZFSA and "ZESA, while contact l6 of relay ZTR again alternately establishes the circuits of the two portions of the primary winding of the transformer 1T so that relay IR receives energy from the impulse transformer IT and contact ii of relay IR operates to establish the circuit for supplying impulses of feed back energy of normal polarity to the rails i and 2. When impulses of feed back energy of normal polarity are received at the leaving end of section 2T, relays PVR and NVR operate as previously described and energy is again supplied to relays PFSA and PBSA. When the contact 48 of relay PFSA picks up, it interrupts the circuit for supplying energy to the lamps of signal S3, and these lamps are thereby extinguished. When relay PFSA picks up, its contacts 42 and @5 again establish the circuit previously traced for supplying to the winding 40 of relay NVR energy of a polarity such that the contacts of relay NVR are moved to their normal position each time that contact 44 of relay CTM moves to its picked-up position. Additionally, the approach-controlled circuit is again supplied with energy over front contact 48 of relay PBSA and front contact 58 of relay PFSA. The equipment is now in its normal condition as was previously explained.

Referring to Fig. 2, there is shown therein a modification of the equipment shown in Fig. l at the leaving end of section 2T. The arrangement of equipment for supplying master code energy to section rails I and 2, the circuit for supplying energy to signal S3, and the approach-controlled circuit are similar to the corresponding circuits previously described in connection with Fig. 1 and a detailed description of their arrangement is unnecessary.

In the modification shown in Fig. 2, when an impulse of feed back energy of normal polarity is received at the leaving end of track section 2T, the energy flows from rail I over back contact I2 of relay CTM, through the winding 23 of relay NVR from right to left, and through the winding of relay PVR from right to left to rail 2. The flow of energy is in a direction such that the contact of relay NVR is operated to its reverse position, while the contact of relay PVR, moves to its picked-up position. At the end of the impulse of energy supplied over the track rails the relay PVR releases, but the contact of relay NVR remains in its reverse position.

When contact I2 of relay CTM moves to its picked-up position, it interrupts the circuit of relays NVR and PVR, and relay PVR releases if it is not already released. In addition, when relay CTM picks up, its contact 44 establishes the circuit for supplying to the local winding 48 of relay NVR energy effective to move the relay contact to its right-hand or reverse position, or to hold it in that position if it is already in its reverse position. As a result it will be seen that the reception of impulses of feed back energy of normal polarity causes the relay PVR to alternately pick up and release its contact while the relay NVR maintains its contact in its reverse position.

At this time relay PFSA is supplied with energy over the circuit established by front contact 35 of relay PVR, while relay PBSA is energized by current supplied over the circuit which is traced from terminal B over back contact 36 of relay PVR, over front contact 60 of relay PFSA, over reverse polar contact 38 of relay NVR, and through the winding of relay PBSA to terminal C. Accordingly, at this time relays PFSA and PBSA are both energized and energy is supplied to the approach-controlled circuit over front contact as of relay PBSA and front contact 53 of relay PFSA. In addition, contact 48 of relay PBSA interrupts the circuit for supplying energy to the lamps of signal S3.

When impulses of feed back energy of reverse polarity are received at the leaving end of section 2T, the energy flows from rail 2, through the winding of relay PVR from left to right, through the winding 26 of relay NVR from left to right, and over back contact I 2 of relay CTM to rail I. As a result, the contact 36 of relay PVR remains in its released position and the contact 33 of relay NVR is operated to its left-hand or normal position. When relay CTM picks up, its back contact I Z interrupts the circuit for connecting relays PVR and NVR acros the rails I and 2, and contact 36 of relay PVR remains in its released position. When relay CTM picks up, its front contact d4 establishes the circuit for supplying energy to the local winding M of relay NV R, and the direction of flow of energy through this winding is such that contact 38 of relay N VB is operated to its reverse position.

On subsequent release of relay CTM its contact 44 interrupts the supply of energy to the local winding ill of relay NVR but the operating characteristics of relay NVR are such that itscontact 38 remains in its reverse position until an impulse of energy is supplied over the track rails to the winding 26 of relay NVR.

Accordingly, it will be seen that when coded feed back energy of reverse polarity is received at the leaving end of section 2T, the contact 36 of relay PVR remains released, and the contact 38 of relay NVR is operated to its normal position by the impulses of feed back energy and is operated to its reverse position by energy supplied to its winding 40 from the local source of energy during the intervals in which the contacts of relay CTM are picked up. At this time, as contact 36 of relay PVR remains in its released position, the supply of energy to relay PFSA is interrupted, and after a time interval its contacts release.

During the time interval between the release of contact 36 of relay PVR and the release of the contacts of relay PFSA, the relay PBSA is supplied with energy by the circuit which is traced from terminal B over back contact 36 of relay PVR, over front contact 60 of relay PFSA, over reverse contact 38 of relay NVR, and through the winding of relay PBSA to terminal C. After the contacts of relay PFSA release, relay PBSA is sup-plied with energy by the circuit which is traced from terminal B over back contact 35 of relay PVR, over back contact 50 of relay PFSA, over normal contact 38 of relay NVR, and through the winding of relay PBSA to terminal C. Accordingly, it will be seen that on the change in the polarity of the feed back energy, the relay PBSA is supplied with energy effective to keep the relay contacts picked up.

After relay PFSA releases, the relay PBSA serves as a code detecting relay for the reverse code following relay N'VR, and energy is supplied to the winding of relay PBSA each time that an impulse of feed back energy operates the contact of relay NVR to its normal position.

At this time the supply of energy to the approach-controlled circuit is interrupted by contact 50 of relay PFSA. However, contact 48 of relay PBSA remains picked up to interrupt the circuit for supplying energy to the lamps of signal S3.

When the feed back energy supplied from the entering end of section 2T is interrupted, for example, by the entrance of a train into section 2T, the supply of energy to the winding of relay PVR and to the winding 26 of relay NVR is interrupted. As relay PVR remains released energy is not supplied to relay PFSA and its contacts release if they are not already released.

If at the time the supply of energy to the winding 2-3 of relay NVR is interrupted, the contact 38 of relay NVR is in its normal position, the energy supplied to the local winding 40 of relay NVR during the next movement of contact 44 of relay CTM to its picked-up position will operate the contact 38 of relay NVR to its reverse position. Should the supply of energy to winding 25 of relay NVR be interrupted at a time when contact 38 occupies its reverse position, energy thereafter supplied to the winding 40 of relay NVR will maintain the contact 38 in its reverse position. Since energy is no longer supplied to the winding 28 of relay NVR to operate the contact 38 to its normal position, contact 38 will remain in its reverse position, succeeding impulses of energy supplied to the local winding 40 only serving to maintain the contact in that position.

When relay PFSA is released and contact 38 of relay NVR is in its reverse position, the supply of ii energy to relay PBSA is interrupted and after a short time interval contacts of relay PBSA release. Accordingly, the circuit for supplying energy to the approach-controlled circuit is interrupted by contact 38 of as by contact 58 of relay PFSA, while the closing of back contact 58 of relay PBSA causes energy to be supplied to the lamp of signal S3 selected by the contact of relay 3BSA.

It is now assumed that feed back energy is again supplied over the rails of section 2T and that this energy is of normal polarity. Energy will flow from rail I over back contact 52 of relay CTM, through Winding 26 of relay NVR from right to left, and through the winding of relay PVR from right to left to section rail 2. Accordingly, each impulse of feed back energy will cause the contact 38 of relay NVR. to move to its reverse position, and will cause contact 36 of relay PVR to move to its picked-up position. Impulses of energy supplied from the local source to winding 46 of relay NVR, which are governed by front contact 2 3 of relay CTM, will serve to maintain contact 38 of relay NVR in its reverse position. As a result, as explained above, the relays PFSA and PBSA are energized and their contacts move to their picked-up positions. When contact 48 of relay PBSA picks up, it interrupts the supply of energy to the lamps of signal S3, and when contact 56 of relay PFSA picks up, it cooperates with contact 48 of relay PBSA to again supply energy to the approach-controlled circuit. The equipment is now in its normal condition as was previously described.

Referring to Fig. 3 of the drawings, we have shown therein cut section facilities which are suitable for use with the equipment shown in Figs. 1 and 2. These facilities are required when, because of excessive length or for any other reason it becomes necessary to subdivide the track section into two or more track circuits. In Fig. 3, one such cut section is shown and to facilitate explanation it will be assumed that this particular location is constituted by interposing insulated rail joints 3 between the entering and leaving ends of section 2T of Fig. 1, dividing the original section 2T into a section 2T extending from the entering end of the section to the out section, and a section ZAT extending from the cut section to the leaving end of the original section 2T. It is to be understood that either the equipment shown at the leaving end of section ET in Fig. l or that shown in Fig. 2 may be used at the leaving end of section 2AT.

The facilities of Fig. 3 are arranged to perform two functions. First, they repeat the impulses of master code energy received from the leaving end of section ZAT around the insulated joints 3 and into the rails of section 2T. Aiding in this first function is a code following track relay ZATR which is operated by the energy received from the rails of section 2AT, a track battery 2TB which serves as an energizing source for the rails of section ET, and a coding contact 56 operated by the relay TR and arranged to complete the rail supply circuit for the rear section each time that the track relay ZATR picks up its contacts and to interrupt it each time that the relay releases its contacts.

As in the corresponding arrangements in Figs. 0'

l and 2, the referred to rail supply circuit of Fig. 3 is traced from the positive terminal of battery 2TB over front contact 66 of relay 2ATR, track rails I and 2 of section 2T, and back to the negative terminal of battery 2TB.

relay PBS-A as well a Cal The second function performed by the cut section facilities of Fig. 3 is to repeat the impulses of feed back energy from section 2T around the insulated joints 3 into section 2AT. Participating in this second function are the code followin relays PVR and NVR, with their associated slow release relays PFSA and PBSA; a feed back battery ZAFB; a relay IR, which, as in Fig. 1, transfers the rail connection from the winding of track relay ZATR to the battery ZAFB; and a transformer IT which supplies relay IR with a pulse of pick-up energy each time that relay 2ATR releases its contacts.

With the equipment in its normal condition as shown in the drawings, impulses of master code energy are supplied from the rails I and 2 of section ZAT to track relay ZATR by a circuit which traced from rail I over back contact it of relay IR, and through the winding of track relay ZATR to rail 2. With relay ZATR, picked up, energy is supplied to the rails l and 2 of track section ET by the circuit which is traced from the positive terminal of battery 2TB, over front contact 6 of relay ZATR, rails l and 2, and back to the negative terminal of battery 2TB.

When track relay ZATR, releases at the end of each impulse of master code energy, relay IR receives an impulse of energy from the impulse transformer IT, as explained in connection with Fig. 1, and its contact i l picks up for a short time interval, interrupting the connection of relay EATR to, rails l and 2 of section 2AT, and supplying an impulse of feed back energy from the battery ZAFB- to the rails I and 2 of section EAT. This energy may be of normal or reverse polarity, as determined by the contacts 68 and 69 of relay PBSA, and contacts H and T2 of relay PFSA. Relays PFSA and PBSA are controlled in a manner which will be subsequently .explained.

During the intervals in which contact 56 of relay ZATR is released, the relays PVR and NVR are connected in series across the rails of section 2T and may respond to impulses of feed back energy supplied over the section rails. Re-

lays PVR and NVR are of a type the contacts of which pick up when and only when energy flows through the winding in the direction shown by the arrows and these relays are connected across the rails of section 2T so that they respond to energy of opposite polarities. As a result the contact of relay PVR will pick up and release in response to impulses of feed back energy having normal polarity, that is, when rail l is positive with respect to rail 2, and the contact of relay NVR will pick up and release in response to impulses of feed back energy having reverse polarity, that is, when rail 2 is positive with respect to rail 1.

The circuits for supplying energy to the relays PFSA and PBSA are similar to those previously described in connection with Fig. 2, and are arranged so that relay PFSA and relay PBSA will both be picked up when relay PVR is following code, provided that relay NVB is not operating, and so that relay PBSA only will be picked up when relay NVR is following code, provided that the relay PVR is not operating and relay PFSA is released. A detailed description of the operation of this arrangement is not necessary, being fully explained in connection with Fi 2.

It will be seen that with feed back energy of normal polarity being supplied over rails I and 2 of section 2T, the relay PVR operates so that relays PFSA and PBSA are both energized and their contacts are picked up. At this time feed back energy of the normal polarity is supplied to the rails I and 2 of section ZAT by a circuit which is traced from the positive terminal of bat tery 2AFB over front contact II of relay PFSA, over front contact 58 of relay PBSA, and over front contact I4 of relay IR to rail I of section ZAT. The return circuit is traced from rail 2 of section ZAT over front contact 69 of relay PBSA, and over front contact '12 of relay PFSA to the negative terminal of battery 2AFB.

At a time when feed back energy of reverse polarity is received from the entering end of section 2T over rails I and 2, relay PVR remains released and the flow of energy through the winding of relay NVR is such that its contact will pick up. When relay NVR operates, the re lay PBSA is energized provided the contact of relay PVR is in its released position and the contacts of relay PFSA are in their released position. It will be seen therefore that at this time the contacts of relay PBSA are picked up and the contacts of relay PFSA are released. Feed back energy of reverse polarity is now supplied from battery ZAFB to the rails I and 2 of section 2A1 over the circuit which is traced from the positive terminal of battery 2AFB over back contact I?! of relay PFSA, and over front contact 69 of relay PBSA to rail 2, and from rail I over front contact I 4 of relay IR, front contact 68 of relay PBSA, and over back contact TI of relay PFSA to the negative terminal of battery ZAFB.

If at any time the contacts of relay PFSA are picked up due to the fusing or sticking of the contact 36 of relay PVR in its picked-up position, it will be seen that the supply of energy to relay PBSA is interrupted, and the contacts of this relay will release. At this time feed back energy of reverse polarity is supplied from battery ZAFB to the rails I and 2 of section ZAT over the circuit which is traced from the positive terminal of battery ZAFB over back contact 69 of relay PBSA to the rail 2 of section 2A'I, and from rail I of section ZAT over front contact I4 of relay IR and over back contact 58 of relay PBSA to the negative terminal of battery ZAFB.

As explained in connection with Fig. 1, feed back energy of normal polarity is employed to control safety or vital functions, while feed back energy of reverse polarity is employed to control non-safety functions. Since the cut section ap paratus is arranged so that feed back energy of normal polarity is supplied to the rails of section ZAT only when relays PFSA and PBSA are both picked up, it follows that the circuits at the exit end of section ZAT which depend on receipt of feed back energy of normal polarity will not be established unless relays PFSA and PBSA at the cut section are both picked up.

In operation, when the stretch is vacant the cut section equipment shown in Fig. 3 operates to repeat into section 2T the master code energy supplied to the rails of section ZAT. As long as traffic conditions are such that the feed back energy supplied to the rails of section ET is of normal polarity the relay PVR is operated and causes relays PFSA and PBSA to be energized so that the feed back energy supplied to the rails of section 2AT is of normal polarity and the code detecting means at the exit end of this section will operate to establish the approach-controlled circuit.

When traffic conditions are such that the feed back energy supplied to the rails of section 2T is of reverse polarity the relays PVR and PFSA are released while relay NVR operates and establishes the circuit of relay PBSA. As relay PFSA is released, the feed back energy supplied to the rails of section 2AT is of reverse polarity even though relay PBSA is picked up. As the feed back energy supplied to the rails of section 2AT is of reverse polarity, the code detecting means at the exit end of the section ceases to establish the approach-controlled circuit, but will continue to interrupt the circuit of the lamps of the wayside signal at that point. At the cut section, as relay PBSA is energized its contact 14 interrupts the circuit controlled thereby. This circuit may be employed for any appropriate purpose, as for example, for controlling the supply of alternating current to the rails of section 2T to govern cab signal apparatus on a locomotive in the section.

When a train moving in the normal direction of traffic enters section 2T, the supply of feed back energy over the section rails is cut off and the relays PVR and NVR both remain released with the result that relays PFSA and PBSA both become released. On release of relay PBSA its contact M establishes the circuit controlled thereby, while contacts 68 and 69 of relay PBSA establish connections independent of the contacts of relay PFSA for supplying feed back energy of reverse polarity from battery ZAFB to the rails of section 2AT. At this time, therefore, feed back energy of reverse polarity continues to be supplied to the rails of section ZAT and the equipment at the exit end of the section continues to interrupt the circuit of the lamps of the wayside signal at that location.

When the train advances into section ZAT the relay ZATR remains released so relay IR ceases to operate to supply energy from battery ZAFB to the rails of section 2AT. As a result, the equip ment at the exit end of section 2AT operates to establish the circuit of the lamps of the wayside signal at that location and to continue to interrupt the approach-controlled circuit. As relay ZATR remains released, energy is not supplied from battery 2TB to the rails of section 2T so the equipment at the entrance end of this section does not operate to supply feed back energy to the section rails. Accordingly, when section 2T is vacated the relays PVR, NVR, PFSA and PBSA remain released.

When the train vacates section ZAT master code energy supplied at the exit end of the section again feeds to relay ZATR and operates it to supply energy from battery 2TB to the rails of section 2T and to cause relay IR to operate to supply impulses of feed back energy from battery ZAFB to the rails of section ZAT. As a result of the supply of master code energy to the rails of section 2T the equipment at the entrance end of the section again operates to supply to the section rails impulses of feed back energy of one polarity or the other depending on traflic conditions in the rear. If this energy is of normal polarity it will operate the relay PVR to pick up relays PFSA and PBSA and the equipment will again be in the condition shown in the drawings.

Accordingly, it will be seen that the cut section arrangement of Fig. 3 embodying our invention may be interposed within the limits of a section of track, such as shown in Fig. 1, without interfering with the operation of master code equipment or the feed back code equipment at the extreme limits of the section, and providing for repeating the master code and the feed back code in accordance with that received.

While we have explained our invention in an application wherein a polarized feed back coded track circuit is utilized, it is to be understood that our invention may be used in any application where it is desired to detect the code following operation of two relays, one of which is to control a safety function and the other of which is to control a non-safety function.

Although we have herein shown and described only three forms of coded signaling apparatus embodying our invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of our invention.

Having thus claim is:

1. In a coded signaling system, in combination, a first code following relay having contacts which are at times operated between a first and a second position, a second code following relayhaving contacts which are at times operated between a first and a second position, a first and a second slow release relay, a circuit'including a contact of said first code following relay closed when the relay contacts are in their second position for supplying energy to said first slow release relay, a circuit including a contact of said first code following relay closed when the relay contacts are in their first position and also including a front contact of said first slow release relay for supplying energy to said second slow release relay, a circuit including a contact of said second code following relay closed in a predetermined one of the two positions of the contacts of said relay and also including a back contact of said first slow release relay for also supplying energy to said second slow release relay, a control circuit governed by front contacts of said first and second slow release relays in series, and a control circuit governed by a contact of said second slow release relay.

2. In a coded signaling system, in combination, a first code following relay having contacts which are at times operated between a first and a second position, a second code following relay having contacts which are at times operated between a first and a second position, a first and a second slow release relay, a circuit including a contact of said first code following relay closed when the relay contacts are in their second position for supplying energy to said first slow release relay,

a circuit including a contact of said first code following relay closed when the relay contacts are in their first position and also including a front contact of said first slow release relay for supplying energy to said second slow release relay, a circuit including a contact of said second code following relay closed in a predetermined one of the two positions of the contacts of said relay and also including a back contact of said first slow release relay and a contact of said first code following relay closed when the contacts, of said first code following relay are in their first position for also supplying energy to said second slow release relay, a control circuit governed by front contacts of said first and second slow release relays in series, and a control circuit governed by a contact of said second slow release relay.

3. In a coded signaling system, in combination, a pair of conductors to which coded energy of normal polarity is at times supplied and to which coded energy of reverse polarity is at other times described our invention, what we l6 supplied, a first and a second code following relay each having a contact biased to a released position and movable therefrom to a picked-up position when and only when energy fiows through the relay winding in a selected direction, the windings of said relays being connected across said conductors in such manner that energy of normal polarity flows through the winding of said first code following relay in said selected direction and energy of reverse polarity fiows through the winding of said second code following relay in said selected direction, a first and a second slow release relay, a circuit including a front contact of said first code following relay for supplying energy to said first slow release relay, a circuit including a back contact of said first code following relay and a front contact of said first slow release relay for supplying energy to said second slow release relay, a circuit including a front contact of said second code following relay, and a back contact of said first slow release relay for also supplying energy to said second slow release relay, a control circuit governed by front contacts of said first and second slow release relays in series, and a control circuit governed by a contact of said second slow release relay.

4. In a coded signaling system, in combination, a pair of conductors to which coded energy of normal polarity is at times supplied and to which coded energy of reverse polarity is at other times supplied, a first and a second code following relay each having a contact biased to a released position and movable therefrom to a picked-up position when and only when energy flows through the relay winding in a'selected direction, the windings of said relays being connected across said conductors in such manner that energy of normal polarity flows through the winding of said first code following relay in said selected direction and energy of reverse polarity fiows through the winding of said second code following relay in said selected direction, a first and a second slow release relay, a circuit including a front contact of said first code following relay for supplying energy to said first slow release relay, a circuit including a back contact of said first code following relay and a front contact of said first slow release relay for supplying energy to said second slow release relay, a circuit including a front contact of said second code following relay and back contacts of said first code following and first slow release relays for also supplying energy to said second slow release relay, a control circuit governed by front contacts of said first and second slow release relays, and a control circuit governed by a contact of said second slow release relay.

5. In a coded signaling system, in combination, a pair of conductors to which impulses of energy of one polarity are at times supplied and to which impulses of energy of the other polarity are at other times supplied, first code following relay having a contact biased to a released posit n and movable therefrom to a picked-up position when and only when energy flows through the relay winding in a selected direction, a polarized code following relay having a contact which is moved to a first or a second position according as energy of one polarity or the other is supplied to a winding of the relay, a transmitter relay having contacts which are recurrently operatcd between a first and a second position, said transmitter relay being effective when its contacts are in their first position to connect said code following relays across said conductors so I? that the contact of said first code following relay is picked up only by energy of said one polarity supplied over said conductors and so that the contact of said polarized code following relay is moved to its first or its second position according as energy of said one or said other polarity is supplied over said conductors, said transmitter relay being effective when its contacts are in their second position to establish a circuit for supplying to a winding of said polarized relay energy effective to move the relay contact to its first position, a circuit including a front contact of said first code following relay for sup plying energy to a first slow release relay, a circuit including a back contact of said first code following relay and a front contact of said first slow release relay for supplying energy to a second slow release relay, the contact of said polarized relay being effective when in its second position to establish a circuit including a back contact of said first slow release relay for also supplying energy to said second slow release relay, a control circuit governed by front contacts of said first and second slow release relays in series, and a control circuit governed by a contact of said second slow release relay.

6. In a coded signaling system, in combination, a pair of conductors to which impulses of energy of one polarity are at times supplied and to which impulses of energy of the other polarity are at other times supplied, a first code following relay having a contact biased to a released position and movable therefrom to a picked-up position when and only when energy fiows through the relay winding in a selected direction, a polarized code following relay having a contact which is moved to a first or a second position according as energy of one polarity or the other is supplied to a winding of the relay, a transmitter relay having contacts which are recurrently operated between a first and a second position, said transmitter relay being effective when its contacts are in their first position to connect said code following relays across said conductors so that the contact of said first code following relay is picked up only by energy of said one polarity supplied over said conductors and so that the contact of said polarized code following relay is moved to its first or its second position according as energy of said one or said other polarity is supplied over said conductors, said transmitter relay being effective when its contacts are in their second position to establish a circuit for supplying to a winding of said polarized relay energy effective to move the relay contact to its first position, a circuit including a front contact of said first code following relay for supplying energy to a first slow release relay, a circuit including a back contact of said first code following relay and a second position contact of said polarized code following relay for supplying energy to a second slow release relay, a control circuit governed by front contacts of said first and second slow release relays in series, and a control circuit governed by a contact of said second slow release relay.

7. In a coded signaling system, a first and a second code following relay operated by coded energy supplied over a pair of conductors, said first code following relay having a contact biased to a first position and at times operated between said first and a second position by energy of a given character supplied over said conductors, said second code following relay having a contact which at times is operated from a first to a 18 second position by energy of a character different from said given character supplied over said conductors and for which energy of different character the contact of said first code following relay remains in its first position, local biasing means for at times operating said second code following relay, means for selectively detecting operation of said code following relays comprising a first and a second slow release relay, a circuit including a second position contact of said first code following relay for supplying energy to said first slow release relay, circuit means including a first position contact of said first code following relay for supplying energy to said second slow releaserelay provided the contact of said second code following relay is in a selected one of its two positions, said selected position of the contact of said second code following relay being that effected by said local biasing means when said first code following relay is following code and being that eifected by said energy of different character supplied over said conductors when the first code following relay is not following code, a control circuit governed by front contacts of said first and second slow release relays in series, and a circuit governed by a contact of said second slow release relay.

8. In a coded signaling system, a first and a second code following relay operated by coded energy supplied over a pair of conductors, said first code following relay having a contact biased to a released position and movable therefrom to a picked-up position when and only when energy of normal polarity is supplied to said relay over said conductors, said second code following relay having a contact which is moved from a first to a second position by energy of reverse polarity supplied over said conductors, local biasing means for at times operating the contact of said second code following relay, means for selectively detecting operation of said code following relays comprising a first and a second slow release relay, a circuit including a front contact of said first code following relay for supplying energy to said first slow release relay, circuit means including a back contact of said first code following relay and a selected one of the positions of said contact of said second code following relay for supplying energy to said second selected position of the contact of said second code following relay being that effected by said local biasing means when said firstcode following relay is following code and being that effected by said energy of reverse polarity supplied over said conductors when the first code following relay is not following code, a control circuit governed by front contacts of said first and second slow release relays in series, and a control circuit governed by a contact of said second slow release relay.

9. In a coded signaling system, in combination, a pair of conductors to which impulses of energy of one polarity are at times supplied and to which impulses of energy of the other polarity are at other times supplied, a first code following relay having a contact biased to a released position and movable therefrom to a picked-up position when and only when energy flows through the relay winding in a selected direction, a polarized code following relay having a contact which is moved to a first or a second position according as energy of one polarity or the other is supplied to a winding of the relay, a transmitter relay having contacts which are recurrently operated between a first and a second position, said slow release relay, said 19 transmitter relay being effective when its contacts are in their first position to connect said code following relays across said conductors so release relay to which energy is supplied over acircuit including a front contact of said first code following relay, said transmitter relay being efiective when its contacts are in their second position to establish a circuit for supplying to a winding of said polarized relay energy effective according as the contacts of said first slow release relay are picked up or are released to move the contact of said polarized relay to its second or its first position, a second slow release relay to which energy is supplied over a circuit including a back contact of said first code following relay and a second position contact of said polarized code following relay, a control circuit governed by front contacts of said first and second slow release relays in series, and a control circuit governed by a contact of said second slow release relay.

HERMAN G. BLOSSER.

FRANK H. NICHOLSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,021,654 Kemmerer et a1. Nov. 19, 1935 2,164,668 Sorensen July 4, 1939 Sorensen Nov. 12, 1940 

